FIG. 1 is a structural diagram of a security sublayer applied to a broadband wireless access system.
Referring to FIG. 1, in a broadband wireless access system, as a security requirement, authentication, privacy of data and integrity of data are provided using a PKM(privacy and key management) protocol.
An authentication procedure is carried out via validity update of an authentication key in case that a mobile station enters a network. The authentication procedure can be also carried out using RSA (Rivest, Shamir, Adleman) or EAP (extensible authentication protocol) authentication protocol in case that a mobile station performs a handover.
In order to secure data confidentiality and data integrity between a mobile station and a base station, SA (security association) is established. The SA includes a data encryption key used for the security of the data encryption and integrity in transmission of user data between a base station and a mobile station, and includes a cryptographic suite of an initialization vector and the like.
And, the PKM protocol enables protection against threats such as a replay attack by an unauthorized user and the like in a manner of defining an authentication key update procedure via re-authentication and an encryption key update procedure and the like.
FIG. 2 is a diagram to explain a communication performing method using a relay station according to a related art.
Referring to FIG. 2, a relay station can be used for service coverage extension and data throughput improvement. In particular, a relay station plays a role as a relay between a mobile station and a base station, whereby a service area is extended or higher data throughput can be provided. A network including the relay station has a tree structure where a base station is a terminal point of a relayed data path.
Meanwhile, the relay station is compatible with a conventional PMP (point-to-multipoint) system. And, a frequency band of the relay system can be equal to or be adjacent to that of the PMP system. The relay station includes a fixed relay station, a nomadic relay station and a mobile relay station.
FIG. 3 is a diagram to explain operations of a relay station according to a related art.
Referring to FIG. 3, a relay station includes a relay station 32 for data throughput improvement and a relay station 34 for service coverage extension.
The relay station 32 for data throughput improvement relays user data exchanged between a mobile station 33 and a base station 31. But, a control message broadcasted from the base station 31 or an uplink control message transmitted from the mobile station 33 is directly transmitted or received between the base station 31 and the mobile station 33.
The relay station 34 for service coverage extension relays user data exchanged between the mobile station 35 and the base station 31 and also relays a control message broadcasted from the base station 31 or an uplink control message transmitted from the mobile station 35.
So, compared to the directly transmitted data, the relayed data have one or more frame delays. Meanwhile the relay station is able to raise overall data throughput by transmitting data in a manner of applying modulation and coding schemes according to a channel status. In a broadband wireless access system, authentication and data encryption procedure between a mobile station and a base station in link layer can be provided for security. A relay station in the broadband wireless access system relays data between the base station and the mobile station. And, a necessary signaling procedure can be provided for list control of mobile stations communicating with the relay station between the relay station and the base station or between the relay station and each mobile station. Moreover, in case that a mobile station performs a handover, a relay station may be involved in the handover.
As mentioned in the foregoing description, in order to define control signaling in MAC layer between a base station (or a relay station) and a mobile station and to control coding and modulation of relayed data, an authentication procedure for the relay station is needed.
However, the related art fails to provide the authentication and security associated procedures for the relay station.